Abstract 1973: RIP1 and its signaling network regulate radiation-induced modification of cancer microenvironment

Abstract

Abstract Radiotherapy is the principal treatment method for inducing cell death in various cancer types such as lung cancer; however, this therapeutics is frequently associated with occurrence of resistance such as recurrences or metastasis due to recent studies that radiotherapy might promote cancer progression and metastasis. Recurrences or metastasis is major cause of treatment failure of cancer, but its intra-/inter-cellular molecular mechanisms was not identified clearly yet due to the fact that genetic characteristics of cancer are extremely diverse according to individuals. Therefore, the objective of this study is to investige the modifications of intracellular signaling/genetic profiling in ionizing radiation (IR)-irradiated microenvironment of non-small-cell lung cancer (NSCLC), and to provide new therapeutic target for treatment of metastatic cancer. Previously, we have studied that IR treatment increased migration and invasion via induction of epithelial-mesenchymal transition (EMT) in A549 cells. With the same system, we found the increase of expression level of receptor interacting protein 1 (RIP1) in IR-treated A549, and this increased expression of RIP1 is associated with IR-induced EMT induction in vitro. NCI-H460 and A549 overexpressing RIP1 was established, and these transfectants also showed increased of migration and invasion via EMT induction. Signaling analyses indicated activation of EGFR-Src-STAT3 pathway is required for the EMT induction, and RIP1 exerts effect on this pathway resulting in activation of EGFR- RIP1-Src-STAT3 pathway. The down-regulation of RIP1 expression by treatment of siRNA, pharmaceutical inhibitor for RIP1 kinase, or dominant negative mutant of the kinase suppressed not only the activation of EGFR-RIP1-Src-STAT3, but also the EMT induction; this suggests that RIP1 might be one of key molecules in IR-induced migration/invasion. Additionally, DNA profiling analyses of RIP1-overexpressed NCI-H460 and A549 indicated that IL-1β is the most prominent over-expressed gene in common. IR treatment also stimulated IL-1β expression and its upstream NF-κB activation via increase of RIP1 followed by induction of EMT and cancer invasion/migration. Supernatants of stable cells including secreted IL-1β treatment promoted invasion/migration of NCI-H460 and A549 cells via EMT induced by activation of EGFR- RIP1-Src-STAT3 pathway. Taken together, our present results imply that RIP1 signals through EGFR- RIP1-Src-STAT3 axis and also through RIP1-NF-κB-IL-1β pathway. This also suggest that these two pathways are connected with common molecule, RIP1, which is novel signaling pathway and activations of these two pathways contribute to new autocrine signaling involving IL-1β secretion; therefore, RIP1 has a role as a novel biomarker as well as a molecular target for suppressing lung cancer metastasis. Citation Format: Jeong Hyun Cho, Jung Lim Kim, Hong-Duck Um, Sang-Gu Hwang, EunAh Lee, Sang-Churl Oh, Jong Kuk Park. RIP1 and its signaling network regulate radiation-induced modification of cancer microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1973.